The Neurons and the NeurotransmittersNeurons
the specialized cells that conduct impulses through the nervous system and contain three major parts - a cell body, dendrites, and an axon
anatomy of a neuroncell body (soma) contains the nucleus and carries out the metabolic, or life-sustaining, functions of a neuron.
dendrites (comes from the Greek word for "tree") and are the primary receivers of signals from the neurons, they look life the leafless branches of a tree
axon is the slender, tail-like extension of the neuron that transmits signals to the dendrites or cell body of other neurons and to muscles, glands, and other parts of the body
works of neurons
afferent (sensory) neurons relay messages from the sense organs and receptors - eyes, ears, nose, mouth, and skin -- to the brain or spinal cord;
efferent (motor) neurons convey signals from the central nervous to the glands and the muscles, enabling the body to move
interneurons (thousand of times more numerous than motor or sensory neurons) carry information between neurons in the brain and between neurons in the spinal cord
Glial Cells are specialized cells in the brain and spinal cord that hold the neurons together, remove waste products, such as dead neurons, from the brain by engulfing and digesting them, and they handle other manufacturing, nourishing and cleanup tasks smaller than neurons and make up more than one-half the volume of the human brain
The Synapse is the junction where the axon terminal of a sending neuron communicates with a receiving neuron across the synaptic cleft.
The Myelin Sheath is a white, fatty coating, wrapped around some axons that acts as insulation
Neurotransmitters
Neurotransmitter is a chemical substance that is released into the synaptic cleft from the axon terminal of a sending neuron, crosses a synapse, and binds to appropriate receptors sites on the dendrites or cell body of a receiving neuron, influencing the cell either to fire or not to fire
why synaptic vesicles can continue to pour out
the cell body of the neuron is always working to manufacture more of the neurotransmitters
unused neurotransmitters in the synaptic cleft may be broken down into components and reclaimed by the axon terminal to be recycled and used again
the process of REUPTAKE - the neurotransmitter is taken from the synaptic cleft back into the axon terminal, intact and ready for immediate use thus terminating the neurotransmitter's excitatory or inhibitory effect on the receiving neuron
the variety of neurotransmitters
acetylcholine (Ach), a neurotransmitter that exerts excitatory effects on the skeletal muscle fibers, causing them to contract so that the body can move and has an inhibitory effect on the muscle fibers in the heart, which keeps the heart from beating too rapidly
Dopamine (DA), one of four neurotransmitters called monoamines, produces both excitatory and inhibitor effects and is involved in several functions, including learning, attention, movement, and reinforcement
Norepinephrine (NE) has an effect on eating habits (it stimulates the intake of carbohydrates) and plays a major role in alertness and wakefulness.
Epinephrine complements norepinephrine by affecting the metabolism of glucose and causing the nutrient energy stored in muscles to be released during strenuous exercise
Serotonin plays an important role in regulating mood, sleep, impulsivity, aggression, and appetite
Glutamate is the primary excitatory neurotransmitter in the brain
GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the brain
Endorphins provide relief from pain or the stress of vigorous exercise and produce feelings of pleasure and well-being
2 divisions of the human nervous system
Central Nervous System (CNS) - composed of brain and the spinal cord
Peripheral Nervous System - connects the central nervous system to all other parts of the body
why is an intact spinal cord important to normal functioning?
the spinal cord is an extension of the brain that reaches from the base of the brain, through the neck, and down the hollow center of the spinal column; it transmits messages between the brain and the peripheral nervous system
the brainstem
brainstem is part of the hindbrain that begins at the site where the spinal cord enlarges as it enters the skull, and it handles functions that are so critical to physical survival that damage to it is life-threatening
medulla is the part of the brainstem that controls heartbeat, breathing, blood pressure, coughing, and swallowing
reticular formation (reticular activating system RAS), plays a crucial role in arousal and attention
the Cerebellum
important to the body's ability to execute smooth, skilled movements
regulates muscle tone and posture
coordinates the series of movements necessary to perform many simple activities without conscious effort
help to heighten ability to focus attention on incoming sensory stimuli and to shift attention
may increase our efficiency in acquiring sensory information and discriminating between sensory stimuli
the Midbrain
lies between the hindbrain & the forebrain
act as relay stations through which the basic physiological functions of the hindbrain are linked to the cognitive functions of the forebrain
substantia nigra is located in the midbrain and is comprised of darkly covered nuclei of nerve cells that control our unconscious motor actions.
the thalamus & hypothalamus
thalamus has two egg-shaped parts, serves as relay station for virtually all the information that flows into and out of the forebrain, including sensory information from all the senses except smell
hypothalamus regulates hunger, thirst, sexual behavior, and a wide variety of emotional behaviors, and internal body temperature
the Limbic Systemgroup of structures in the brain, including the amygdala and the hippocampus, that are collectively involved in emotional expression, memory, and motivation.
amygdala plays an important role in emotion, particularly in response to unpleasant or punishing stimuli
hippocampus is located in the interior temporal lobes and plays a central role in the storing of new memories, the response to new and unexpected stimuli, and navigational ability
plays a role in the brain's internal representation of space in the form of neural maps
the cerebrum
most essential part of the brain is the cerebrum & its cortex
cerebrum is the largest structure in human brain. it is composed of two cerebral hemisphere, the left & right which control movement & feeling on the opposing side of the body
corpus callosum connects the two hemisphere and makes possible the transfer of information and the coordination of activity between them
cerebral cortex is the thin gray outer covering about 1/8 inch thick. it is primarily responsible for the higher mental processes of language, memory & thinking
Cerebral cortexgray outer covering about 1/8 inch thick and is primarily responsible for the higher mental processes
contain sensory input areas where vision, hearing, touchy pressure, and temperature register
motor areas, which control voluntary movement
association areas house memories and are involved in thought, perception, and language
4 lobes of the cerebral hemisphere
motor cortex - a strip of tissue at the rear of the frontal lobes that controls voluntary body movement
plasticity - the brain's capacity to adopt to changes such as brain damage - of the motor cortex is maintained throughout life
broca's area - involved in directing the pattern of muscle movement required to produce speech sounds in the left hemisphere of the brain
frontal association areas -involves thinking, motivation, planning for the future, impulse control, and emotional responses
frontal lobes - begin at the front of the brain and extend to the top center of the skull. they contain the motor cortex, Broca's area, and the frontal association
areas
the Parietal Lobes - lie directly behind the frontal lobes, in the top middle portion of the brain and are involved in the reception and processing of touch stimuli
somatosensory cortex,, the site where touch, pressure, temperature, and pain register in the cerebral cortex
the Occipital Lobes at the rear of the brain are involved in the reception and interpretation of visual information
at the very back of the occipital lobes is the primary visual cortex, the site where vision registers in the cortex
the Temporal Lobes, located slightly above ears, are involved in the reception and interpretation of auditory stimuli. the site in the cortex where the hearing registers is known as the primary auditory cortex
wernicke's area - is located adjacent to the primary auditory cortex in the left temporal lobe. this is the language area involved in comprehending the spoken word and in formulating coherent written and spoken language
wernicke's asphasia is a type asphasia resulting from damage to wernicke's area
wernicke's patient when asked how he was feeling, replied " i that there's an awful lot of mung, but i think i've a lot of net and tunged in a little wheat duhvayden" (Buckingham & Kertesz, 1974)
auditory asphasia (word deafness) - the person may hear normally but may not be able to understand spoken language
the cerebral hemisphereLeft hemisphere - handles most of the language functions, including speaking, writing, reading, speech comprehension, and comprehension of the written information
Right Hemisphere - (controlling the left side of the body) more adept at visual spatial relations
auditory cortex in the right hemisphere appears to be far better able to process music that the left
augments left hemisphere's language-processing activities'/ (figures out what its meant and who says it) (e.g the balancing act)
the right hemisphere's role in emotion
responds to the emotional message conveyed by another's tone of voice
reading and interpreting nonverbal behavior
involve in the expression of emotion through tone of voice and facial expression
brain mechanisms responsible for negative emotions are located in the right hemisphere
the Peripheral Nervous System
PNS is made up of all the nerves that connect the central nervous system to the rest of the body
2 subdivisions of the PNS
somatic nervous system -
(1) compose of all the sensory nerves which transmits information from the sense receptors - the eyes, ears, nose, tongue, and skin -- to the central nervous system,
(2) all the motor nerves, which relay messages from the central nervous system make it possible for you to sense your environment and to move, and they are primarily under conscious control
autonomic nervous system -
operates without any conscious control or awareness
transmits messages between the CNS and the glands, the cardiac (heart) muscle, and the smooth muscles (such as those in the large arteries and the gastrointestinal system)
ANS is further divided into 2 parts - the sympathetic & the parasympathetic nervous system
sympathetic nervous system automatically mobilizes the body's resources, preparing you for action
parasympathetic nervous system brings these heightened bodily functions back to normal
the Endocrine System
Endocrine system is a series of ductless glands located in various parts of the body, that manufactured and secrete the chemical substances known as hormones, and secrete them into the bloodstream, thus affecting cells in other parts of the body
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